Apparatus for casting metal slabs and billets

ABSTRACT

The present invention discloses a mold wherein molten metal is introduced to a riser communicating with the mold so that the level at which the molten metal flows into the mold is progressively raised as the mold cavity fills, and simultaneously pressure is applied to a movable bottom for the mold to slowly lift and compress the solidifying metal so that the solidifying metal is constantly rising against newly introduced molten metal to thereby eliminate or substantially reduce shrinkage defects.

United States Patent [72] Inventors Erik A. Olsson Zurich, Switzerland;

Carl-Erik Foogde, Mount Lebanon, Pa. 683,870

Nov. 17, 1967 Aug. 10, 1911 Olsson International Inc.

Pittsburgh, Pa.

Appl. No. Filed Patented Assignee [54] APPARATUS FOR CASTING METAL SLABSAND IILLETS 11 Claims, 6 Drawing Figs.

References Cited UNITED STATES PATENTS 449,701 4/1891 Potter 684,77310/1901 Anderson o o o o o o o 110 3, I 63,898 1/1965 Demaison 249/ 1 743,161,928 12/ 1964 Bishop et a1. 164/54 319,780 6/1885 Billings 249/742,171,229 8/1939 Steiner 164/96 2,283,749 /1942 McBride.... 164/363 X720,374 2/1903 McGratll 164/ 1 20 2,332,956 10/1943 Washton 249/1 191,648,471 11/1927 Austin 1641358 X 714,692 12/1901 Harmet 164/319811,143 1/1906 Harrnet 164/321 746,244 12/1903 Baggaley 164/321 568,51 19/1896 Brooke 164/322 FOREIGN PATENTS 276,773 6/1912 Germany 164/133Primary Examiner.l. Spencer Overholser Assistant Examiner-V. K. RisingAttorney-Parmelee, Utzler & Welsh ABSTRACT: The present inventiondiscloses a mold wherein molten metal is introduced to a risercommunicating with the mold so that the level at which the molten metalflows into the mold is progressively raised as the mold cavity fills,and simultaneously pressure is applied to a movable bottom for the moldto slowly lift and compress the solidifying metal so that thesolidifying metal is constantly rising against newly introduced moltenmetal to thereby eliminate or substantially reduce shrinkage defects.

15 '6 I10 0 c o O o g o o o --15 I o o o o o o 0 0 o o o 0 16 0:? i4 4 oI3 11 Q PATENTED AUG] 0 Ian SHEET 1 BF 3 FIG. 2

Erik A, Olsson 8 Cofl E. Foogde FIG.|

HYDRAULIC POWER SUPPLY Attorneys PATENTEU AUG] 0 l9?! SHEEIEUF 3 Erik A.Olsson Foogde Attorneys 3 INVENTORS a Carl E PATENTED AUG] 01971 3598175I sum 3 BF 3 r 51 FIG. 5

INVENTORS Erik A. O'sson 8: Carl E. Foogde FIGS ,5 214% it:

Attorneys APPARATUS FOR CASTING METAL SLABS'AND BILLETS BACKGROUND OFTHE INVENTION 1. Field of the Invention This invention relates toapparatus for the casting of metal slabs and billets.

2. Description of the Prior Art The prior art is exemplified by U.S.Pat. No. 1,757,549 to Smith, et al. issued May 6, 1930. This patentdiscloses a method and apparatus for the bottom pouring of a pluralityof ingots simultaneously. Beyond that, this patent has no directrelevance to the present invention.

In the usual procedure of casting molten steel into fixed cavity molds,such as ingot molds, solidification occursfrorn the bottom toward thetop, and from the sidewalls toward the center. The cooling of the metalin this manner with the attendant shrinkage results in a cavity or pipe"in the top center of the ingot and shrinkage stresses that may result incracks or fissures in the cast metal.

Summary of the Invention According to the present invention there isprovided apparatus whereby molten metal is poured into a mold cavityfrom a riser or the like positioned adjacent the mold and incommunication therewith so that metal flows from the riser into the moldfrom progressively higher locations as the mold fills. The mold isprovided with a bottom wall and sidewalls movable relatively to eachother to effect a progressive reduction in size of the mold cavitywhereby compressive forces are exerted on the metal during pouring andsolidification to thereby relieve tensile stresses and reduce theformation of skin defects in the metal. The invention may be usedadvantageously with a single mold or with a plurality of molds which arefilled simultaneously from a common pouring riser communicating witheach of the molds. Preferably the bottom wall of the mold is movedupwardly relative to the sidewalls at a rate which will exert a pressureon the metal which is equal to or greater than the ferrostatic pressure.

The present invention improves casting techniques particularly in thecasting of slabs which may be 30 feet or more long, i.e. a mold heightof 30 feet or more. To cast such a slab using conventional techniques isextremely difficult owing to the splashing of metal and blowouts orruptures of the metal skin. As the metal solidifies to form a skin itpulls away from the mold walls and the ferrostatic pressure in theliquid center of the slab causes a rupture of the skin and an escape ofthe metal into the space between the skin and mold wall forming defectsin the slab. The application of a progressive, compres sive force helpsto prevent such ruptures.

An object of the invention is to provide an improved method andapparatus for the casting of metal.

DESCRIPTION OF THE'DRAWINGS FIG. 1 is a vertical section of a pluralmold arrangement according to the invention;

FIG. 2 is a plan view taken along the line 11-11 of FIG. 1;

FIG; 3 isa plan view of another embodiment of a plural mold arrangementaccording to the invention;

FIG; 4 is a perspective view of FIG. 3 with parts broken away;

FIG-5 isa plan view of a single mold embodiment according to theinvention; and

FIG6 is a perspective view of the embodiment of FIG. 5 with partsremoved and parts broken away.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings is asupport member or'stool on which are mounted a plurality of identicalcast iron mold segments 11 and a centrally disposed fountain or riser12. Each mold segment 11 is generally V-shaped as viewed in plan witheach leg of the V forming one sidewall of adjacent mold cavities 13. Aportion of one leg of the V extends at right angles to the leg to formanother sidewall of a mold. For convenience in describing the segments,14 will be referred to as the backface of the segment, 15 to the frontface, and 16 to the face formed by the portion 11a extending at rightangles to the face 15. When the segments are arranged in circularsuccession as shown in H6. 1, with the backface 14 of one segmentconfronting the front face 15 of an adjacent segment with the portionabutting the outer portion of back face 15, there is formed a circularseries of angularly spaced mold cavities 13, three sides of each cavitybeing formed by the sidewalls or faces 14, 15 and 16. Coolant pipes orpassages 21 are provided in each of the mold segments 11 to cool themold faces by flowing water or other suitable coolant through the pipesfrom a suitable source (not shown).

The fourth sidewall of each cavity 13, opposite the side 16 is formed bythe outer face of the central tubular riser 12. The riser 12 comprisesan upright polygonal cylinder made from a frangible refractory materialhaving a solid bottom portion resting on the stool 10, a hollow interiorand, an open top through which metal may be poured into the interior.The outer polygonal surface of the riser constitutes the fourth sidewallof each cavity 13. In the illustrated embodiment there are eight moldcavities 13 so the riser is octagonal. Preferably the vertex edge ofeach V-shaped segment 11 is provided with a notch extending the fullheight of the segment of receiving therein, in abutting relation, thevertex edge defined by each pair of adjacent planes forming the outersurface of the riser. The mold segments and the riser being dimensionedso as to snugly interfit.

The riser 12 is provided with sets of vertically spaced lateral openings12a therein communicating with the hollow interior of the riser and eachof the mold cavities 13. Each opening 12a extends horizontally on aradius from the center of the riser outwardly to each mold cavity, andeach opening lies in a horizontal plane with corresponding openings intoeach of the mold cavities at a given level along the height of theriser. The bottommost openings are spaced above the bottom of the hollowinterior of the riser and the topmost openings are spaced from the topsof the mold cavities. At the top of the riser there is a funnel 22 toaid in pouring metal into the riser.

In the stool 10 there are a plurality of openings 17 through whichextend a plurality of rods 18 each having a block 19 at one end thereofdisposed in a mold cavity 13. Each block 19 is shaped to conform to theinterior of the mold cavities and forms the bottom walls of the molds.The opposite ends of the rods 18 are operatively connected to a suitabledriving means such as a source of hydraulic power indicateddiagrammatically at 20, whereby the rods 18 and therefore the bottomwalls 19 of each mold are vertically movable in the manner of a pistonin a cylinder. They will ordinarily be operated in unison but if desiredeach rod may be separately operated.

In operation the bottom walls 19 are initially bottomed on the stool 10and metal is poured into the riser. When the metal level reaches thelowermost openings 12a metal flows from the riser into the mold cavitieswhere it quickly cools and solidifies to form an outer crust or shell onthe forming slab or billet. Metal also solidifies in the openings 12a atthe height corresponding to the height of the forming slab. Metal flowsfrom the riser into the molds through successively higher sets ofopenings until the molds are all filled to the desired height.

As the metal solidifies in the molds it begins to contract and pull awayfrom the mold walls, which process, if left uncontrolled, would causecracks to form in the slabs. To counteract this, the bottom walls 19 areslowly moved upwardly as the slab is forming to relieve the tensilestresses of contraction in the solidifying skin of the slab andpreferably to place the forming slab under some compression.

When the slabs are all solidified in the molds they are removed and therefractory riser broken away. There will be small projections on thatside of the slab adjacent the riser caused by the solidified metal fromthe openings 12a, these being attached to a solid body of metal thatsolidifies in the tube. These projections can readily be removed by acutting torch or the like. The bottom walls 19 are lowered again and ariser installed for the next cycle of operation.

Referring to FIGS. 3 and 4 there is shown another embodiment of a pluralmold arrangement indicated generally as 30. In this embodiment there aretwo pairs of mold segments 31 and 32 held together by straps 33. Each ofthe segments 31 and 32 are shaped so that when joined together as shownthey define four mold cavities 34 each with four sidewalls, a centralriser 35 and passageways 36 communicating with the riser 35 and moldcavities 34. The whole assembly is mounted on a suitable stool 37.

Each passageway 36 comprises a continuous vertical slot coextensive withthe mold cavity and the riser. Strips 38 are disposed in each of thepassageways 36 at the start of pouring. These strips may be cardboard,aluminum or other suitable materials which will burn away or melt asmetal is poured into the riser. The strips help control the flow ofmetal into the molds to cause the metal to flow from the riser to themolds from progressively higher locations as the molds fill.

Each mold is provided with a hydraulically actuated movable bottom wall39 in essentially the same manner as before described by means ofahydraulic power supply 43 and piston rod 44. Preferably each bottom wallis provided with a covering member 40 made of asbestos or other suitableheat-resistant, flexible material to help seal the bottom wall with themold sidewalls.

The straps 33 are continuous rectangular straps around the mold segmentssecured in place by suitable fastening means such as the bolts 41 whichare received in openings in the end segments 32. When the straps aresecured, wedges 42 of wood, metal or other suitable material are forcedbetween the straps and the side segments 31.

Referring to FIGS. and 6 another embodiment of the in vention isillustrated using a single mold. Two mold segments 50 and 51 are joinedtogether to form a mold cavity and a riser 52 located at one corner ofthe mold. The riser communicates with the mold cavity through acontinuous vertical passageway 53 as in the embodiment of FIGS. 3 and 4.A flow-control strip 54 is inserted between the passageway and the moldcavity in the same manner as before described in connection with FIGS. 3and 4. An asbestos-covered, hydraulically actuated, movable bottom wall55 is provided also as previously described operated by a hydraulicpower supply 56 and rod 57. Straps or other suitable means may beemployed to hold the mold segments 50 and 51 together. As in theembodiment of FIGS. 1 and 2, the embodiments shown in FIGS. 3 to 6 wouldnormally employ a pouring funnel such as funnel 22.

With the invention as described, slabs up to 30 or more feet may be castwith few surface defects and almost no pipe" so as to achieve almost I00percent yield except for the metal which ultimately solidifies in theriser.

The diameter of the riser cavity is preferably on the order of 2 and 4inches depending on the number and size of mold cavities it supplies.

The amount of pressure applied to the bottom walls, the rate of movementand total distance moved depend on the size of slab and the metal beingcast. A heat-resistant flexible cover may be used on the bottom wall ofthe embodiment shown in FIG. I as well as with the other describedembodiments.

In some cases it may be desirable to move the sidewalls relative to thebottom wall, either in a downward direction or laterally, or to moveboth the bottom wall and the sidewalls, or to move one sidewalllaterally, in all cases to reduce the size of the cavity and exert acompressive force on the metal.

While we have described several embodiments ofour invention, it will beunderstood by those skilled in the art that variations thereof arepossible within the scope and spirit of the invention.

We claim:

1. Apparatus for the casting of metal slabs and billets, comprising,

a. a vertically disposed mold having sidewalls and at least one bottomwall forming at least one coreless mold cavib. vertically disposedpouring riser means adjacent the mold and having opening means thereincommunicating with each of the mold cavities and formed such that metalflows into the mold cavities from progressively higher locations as themold cavities fill, and

c. means for effecting the relative vertical movement between the entiremold bottom wall and the sidewalls to reduce the size of the cavitiesduring the pouring and solidification of the metal, whereby as moltenmetal is poured into the riser and flows into the mold cavities throughthe opening means there is exerted a force on the metal as itprogressively solidifies in the mold thereby relieving tensile stresseson the metal as it shrinks during solidification.

2. Apparatus as defined in claim 1 including means for cooling the moldsidewalls.

3. Apparatus as defined in claim 1 including coolant passageways formedin the mold sidewalls, and means for effecting the flow of coolantthrough the passageways.

4. Apparatus for the casting of molten steel into slabs and billetscomprising:

a. a plurality of molds each having sidewalls and a vertically movablebottom wall together forming a coreless mold cavity,

b. a pouring riser having an open top, sidewalls and a bottom wall and avertical succession of horizontal openings in the riser sidewallscommunicating with each of the mold cavities whereby as metal flows intothe riser it flows through successively higher openings into the moldcavities to fill them simultaneously, means for effecting simultaneousvertical upward movement of the entire mold bottom walls relative to thesidewalls of the molds during filling ofthe mold cavities.

5. Apparatus as defined in claim 4 including a pouring funncl at the topofthe riser.

6. Apparatus as defined in claim 4 wherein the riser sidewalls form onesidewall of each of the molds.

7. Apparatus for the simultaneous casting of a plurality of metal slabsor billets, comprising,

a. a series of mold segments each having a front face and a backface,the segments being arranged in circular succession with the front faceof each segment confronting the backface of an adjacent segment to forma circular succession of angularly spaced mold cavities, each pair ofadjacent segments forming three vertical sidewalls of a fourwalled mold,

b. an upright refractory fountain centrally located with respect to thecircular succession of mold segments and forming the fourth sidewall ofeach mold, the fountain having a bottom, an open top, a hollow interior,and a series of lateral openings therein forming passageways for theflow of metal from the hollow interior into each of the mold cavities,there being a like series of vertically spaced openings communicatingwith each of the mold cavities,

c. a bottom wall for each of the molds, and

d. means for moving the bottom walls vertically upward with respect tothe mold sidewalls.

8. Apparatus for the casting of metal slabs and billets comprising:

a. a plurality of vertically disposed molds each having sidewalls and abottom wall forming a coreless cavity,

b. vertically disposed pouring riser means adjacent the molds and havingopening means therein communicating with each mold cavity and formedsuch that metal flows into the mold cavities from progressively higherlocations as the mold cavities fill, and

c. means for effecting relative vertical movement between each entiremold bottom wall and the sidewalls to reduce the size of the cavityduring pouring and solidification of the metal, whereby as molten metalis poured into the riser and flows into each mold cavity through theopenings there is exerted a force on the metal as it progressivelysolidifies in each mold thereby relieving tensile stresses on the metalas it shrinks during solidification.

9 Apparatus for the casting of metal slabs and billets, comprising,

a a pair of mold segments joined together to form the sidewalls of amold cavity,

b. a bottom wall,

c. means for effecting relative vertical movement between the moldsidewalls and the bottom wall during the pouring and solidification ofthe metal to progressively reduce the size of the mold cavity,

d said mold segments defining vertical pouring riser means including anelongated passageway extending substantially over the entire verticalheight of the mold cavity and communicating with the riser and the moldcavity, whereby metal poured into the riser may flow to the cavity, and

e. cover means disposed in the passageway made of a material which isreadily destructible upon contact with molten metal for controlling theflow of metal into the cavity such that the metal flowsfrom thepassageway at progressively higher locations as the mold fills.

10. Apparatus as defined in claim 9 wherein the bottom wall is linedwith a heat-resistant flexible cover.

asbestos.

2. Apparatus as defined in claim 1 including means for cooling the moldsidewalls.
 3. Apparatus as defined in claim 1 including coolantpassageways formed in the mold sidewalls, and means for effecting theflow of coolant through the passageways.
 4. Apparatus for the casting ofmolten steel into slabs and billets comprising: a. a plurality of moldseach having sidewalls and a vertically movable bottom wall togetherforming a coreless mold cavity, b. a pouring riser having an open top,sidewalls and a bottom wall and a vertical succession of horizontalopenings in the riser sidewalls communicating with each of the moldcavities whereby as metal flows into the riser it flows throughsuccessively higher openings into the mold cavities to fill themsimultaneously, c. means for effecting simultaneous vertical upwardmovement of the entire mold bottom walls relative to the sidewalls ofthe molds during filling of the mold cavities.
 5. Apparatus as definedin claim 4 including a pouring funnel at the top of the riser. 6.Apparatus as defined in claim 4 wherein the riser sidewalls form onesidewall of each of the molds.
 7. Apparatus for the simultaneous castingof a plurality of metal slabs or billets, comprisIng, a. a series ofmold segments each having a front face and a backface, the segmentsbeing arranged in circular succession with the front face of eachsegment confronting the backface of an adjacent segment to form acircular succession of angularly spaced mold cavities, each pair ofadjacent segments forming three vertical sidewalls of a four-walledmold, b. an upright refractory fountain centrally located with respectto the circular succession of mold segments and forming the fourthsidewall of each mold, the fountain having a bottom, an open top, ahollow interior, and a series of lateral openings therein formingpassageways for the flow of metal from the hollow interior into each ofthe mold cavities, there being a like series of vertically spacedopenings communicating with each of the mold cavities, c. a bottom wallfor each of the molds, and d. means for moving the bottom wallsvertically upward with respect to the mold sidewalls.
 8. Apparatus forthe casting of metal slabs and billets comprising: a. a plurality ofvertically disposed molds each having sidewalls and a bottom wallforming a coreless cavity, b. vertically disposed pouring riser meansadjacent the molds and having opening means therein communicating witheach mold cavity and formed such that metal flows into the mold cavitiesfrom progressively higher locations as the mold cavities fill, and c.means for effecting relative vertical movement between each entire moldbottom wall and the sidewalls to reduce the size of the cavity duringpouring and solidification of the metal, whereby as molten metal ispoured into the riser and flows into each mold cavity through theopenings there is exerted a force on the metal as it progressivelysolidifies in each mold thereby relieving tensile stresses on the metalas it shrinks during solidification.
 9. Apparatus for the casting ofmetal slabs and billets, comprising, a. a pair of mold segments joinedtogether to form the sidewalls of a mold cavity, b. a bottom wall, c.means for effecting relative vertical movement between the moldsidewalls and the bottom wall during the pouring and solidification ofthe metal to progressively reduce the size of the mold cavity, d. saidmold segments defining vertical pouring riser means including anelongated passageway extending substantially over the entire verticalheight of the mold cavity and communicating with the riser and the moldcavity, whereby metal poured into the riser may flow to the cavity, ande. cover means disposed in the passageway made of a material which isreadily destructible upon contact with molten metal for controlling theflow of metal into the cavity such that the metal flows from thepassageway at progressively higher locations as the mold fills. 10.Apparatus as defined in claim 9 wherein the bottom wall is lined with aheat-resistant flexible cover.
 11. Apparatus as defined in claim 9wherein the cover is asbestos.